Delta sander rheostat?

[xsailer]

I'm wanting to control the RPM's on my 30inch Delta 1.0" belt sander I purchased just a couple of months ago. I'm concerned about burning the motor up and wondering if any of you knowledgeable carvers have any info about controlling speed on the Delta motors?

[millhoused]

I do not know about slowing down your sander. I use mine full speed and have not had a problem. The suggestion of touch then quench works very well. for a detailed explanation see http://www.woodcarvers.com/sharpening.htm . I use an 80 grit belt just like they suggest and it works great.

[Kenny_S]

Bob, I started using my Delta 3 x 21 inch base sander and have a glass of water next to it when I want to sharpen a tool that I have dulled the edge. The motor runs around 3750 RPMs and I just touch the blade to the sanding belt, quinch, touch, quinch, etc till I have the wire edge then buff it. It works.
However, I do like the sharpener that Denny show us at class but for the money, my little Delta sander does the same job without the attachment that Denny had on his.

[Kenny_S]

I forgot to add that if you remember, Denny's sharpener ran in the 3750 RPM area.

[xsailer]

Hello Kenny S, Yes I remember Denny's sharpener. When I got back home I ordered it and have used it with the attachment you talk about and I like it very much. I also use it like you do and as he recommended. I just thought I would like to have the option to slow the speed done a little. I'm very happy with the portability and gouge sharpening. I thought if I could slow it down a little I might be able to use finer grade sanding belts.

[millhoused]

Does anyone have a picture of the Denny sharpener? Or know where I go to get one? I'm addicted to sharpening....

[AlArchie]

Unless you are sure what type of motor is on that unit, DON"T try an electronic speed control on it. Most of those are designed for brush type motors like used on electric drills, sanders, and portable saws. The induction type (brushless) motors will either suffer drastically from either an electronic reducer or a simple rheostat.

An easy way to tell the difference in motors is simply to listen to it. The brush type motors whine while the induction type are almost silent in operation. Also look through the cooling vents....if you see mild sparking, you have a brush type motor.

Also, with those belt type sanders, it's not so much the motor RPM that counts, but rather the belts feet per second (FPS).

To convert RPM to FPS multiply the diameter of the drive wheel, the one that turns the belt by pi (3.14) Fer instance a 2" drive wheel would have a circumference of roughly 6 and a quarter inches. Divide your motor RPM by 60 to get revs per second, so we're working on the same "apple" so to speak. For a 3750 RPM motor that comes out to 62.5 RPS. Just coincidence that both figures are 62.5 and 6.25.

Now simply multiply the 6.25" wheel circumference by the 62.5 RPS to get roughly 390 inches per second or 32.5 feet per second.

Compare that to the FPS of a 6" abrasive wheel spinning at 3750 or 5890 FPS and you can see that the belt speed is nowhere near the wheel speed.

I was just looking at the ad for that "Ultimate Sharpener", and it looks to have a 1725 RPM motor driving a 4" wheel, which would give you the same figures (RPM vs.FPS) as I figured out above, and even if it was a 3750 RPM motor, the belt speed would still only be 65 FPS.

If you convert the 65 fps figure to a rotary wheel, that would put your motor speed at roughly 100 RPM. Just a hair over what that fancy Tormek sharpener spins (90 RPM)



ooops, misplaced a decimal, so that has been corrected. 32.5 fps and 65 fps respectively. Still WAY below the 5890 fps or slower motor 2945 fps.

Al

[Kenny_S]

You can contact Denny Neubauer at
dennyknife@yahoo.com
or
Denny Neubauer
Outback Woodcarving Tools Inc
2413 E 41CT
Des Monies,Iowa,50317

Well worth looking into!

[dart]

I have a Delta 1"x30" belt/disk sander. I removed the disk and mounted an electric drill on the motor shaft. I can vary the speed on the drill motor. I don't run the Delta motor while the drill is running. The bearings on the motor are making a lot of noise and I don't have time to repair it now. Maybe when I get some time I tear it apart and replace the bearings. But for now the drill works really nice. I like to run it on slow speed so it doesn't heat up the tools. I have a 220 grit belt on it for honing.